Parking RV overnight at trailheads within national parks?

Acei wrote:
Say if you own either a truck camper or a trailer, are you allowed to leave your RV at the trailhead parking lots? I'm not talking about huge trailers, may be 24ft maximum or a regular truck camper. This is during those multi-day backcountry camping times.

Each park has it's own rules.

I agree with leaving the camper at a camp site. That's what we did years ago at Yosemite. They have a shuttle bus that goes through the park. I think they had us park in an overflow spot.